1. Field of the Invention
This invention relates generally to the turbine arts and particularly to a novel turbine wheel designed according to fluid-dynamic principles, that is useful for high, medium and low velocity applications and for incompressible and compressible fluids, including vapors and gases of combustion, as well as heavily contaminated fluids such as geothermal steam.
2. Prior Art
Modern turbines for compressible fluids frequently contain a stage consisting of a nozzle or row of nozzles followed by alternating rows of moving and stationary blades. Large turbines may have a succession of compounding actions or multiple stages. Complex and bulky stationary blade assemblies or other stationary devices often redirect or even reverse the fluid flow to properly enter or re-enter the moving blade structures, where all of the mechanical torque is generated. These expensive stationary structures produce no useful output and add to the weight of the turbine. Some energy is lost as the fluid passes through the winding stationary passages.
Turbines for incompressible fluids include the historic undershot, overshot, and horizontal slow speed water wheels, followed by the modern higher speed Pelton, Francis, and propeller types. The use of multiple staging, in which the injected fluid is passed through successive blade systems analogous to those of the compressible fluid turbines, has not been featured in these hydraulic developments. But the critical flow requirements of the stationary guide case, the desirability of adjusting blade angle, and the bearing requirements frequently introduce complexity nevertheless. Aside from the Pelton wheel, the axial direction has been generally featured for fluid entry.
Thus the existing techniques have frequently resulted in complicated designs for all fluids involving such things as counter-rotating wheels, gearing, thrust bearings, spiral guide cases, blade angle adjusting controls, stationary redirecting structures, a plurality of closely-fitted and non-simple blade shapes and other expensive parts for different stages in the same turbine, and sophisticated fabrication.
The important conclusion to be drawn from the above recital is that the mainstream of development in turbines for either compressible or incompressible fluids has not centered on creating an efficient multiple staging system which is totally integral with the turbine wheel. This is achieved in the present invention through effective exploitation of the inward and outward radial directions.
Conventional devices are not completely satisfactory today when any of the following considerations are important: increased simplicity, freedom from thrust bearings or stationary blade structures, a need for an inherently balanced and rugged moving blade structure, ability of a design to be used over a range of operating conditions or to accept contaminated fluid such as geothermal steam without clearance problems, lower cost, factory production limitations as may exist in developing countries, and ready scaling of the same basic turbine wheel design to produce large capacity units or to meet different operating requirements. All of these considerations are facilitated by the present invention through its unique integral multiple staging system.
Although it had been previously unknown to the inventor, a search disclosed the existence of several early but grossly incomplete attempts somewhat in the direction of the present invention. These earlier efforts all failed because they did not contain the requisite elements, or involved impractical arrangements, or included faults in design or concept which were not overcome. These gaps indicate non-recognition of basic problems which must be solved.
Thus the history of the turbine wheel art soon abandoned this particular trend of endeavor and moved on to the developments described in the preceding paragraphs. Without being aware of this background, the present inventor addressed the difficulties which he overcame so that the flaws in the prior art stand out.
Attention is called to the following references:
______________________________________ U. S. PAT. NOS. ______________________________________ 28,682 6/1860 Morehouse 416/178 705,001 7/1902 Widner 415/52 792,143 6/1905 Matthews 415/52 809,711 1/1906 Maier 416/183 985,152 2/1911 Fieroe 416/178 1,127,678 2/1915 Rector 415/52 3,923,416 12/1975 Frey 415/76 ______________________________________ FOREIGN PATENTS OR APPLICATIONS ______________________________________ 7 762 3/1912 Waugh et al Great Britain 364 876 1/1932 Pearson Great Britain 727,519 6/1932 Czernow France 338 358 3/1936 Murtas et al Italy 961,999 5/1950 Courtel et al France ______________________________________